1. Field of the Invention
The present invention relates to a tape library apparatus for allowing an apparatus for recording and reproducing information to and from a recording medium, namely a so-called drive to be easily handled and a controlling method thereof.
2. Description of the Related Art
A system that is capable of storing a plurality of detachable recording mediums (for example, cassette tapes and disc shaped magnetic recording mediums) to a recording and reproducing unit (hereinafter referred to as drive) and recording and reproducing various types of information to and from the stored recording mediums has been used. The system is called a library system or auto changer unit. However, in the following description, the system is referred to as library system.
The library system comprises a cassette console, a drive console, a conveying unit, a so-called elevator, a monitor, and a controlling unit. The cassette console is composed of a plurality of shelves that hold the forgoing recording mediums. The drive console includes a so-called drive that records and reproduces information to and from a recording medium. The elevator is a conveying unit travels among the cassette console, the drive console, and so forth and selectively conveys a recording medium from each shelf of the cassette console to the drive of the drive console. The monitor displays the statuses of the individual consoles and the statuses of the drive and the individual shelves. The controlling unit controls the drive and the conveying unit.
[Patent Document 1]
Japanese Patent Laid-Open Publication No. 2000-149516
The Patent Document 1 is directed to a library system would solve troublesome and inconvenient operation of a conventional system that requires the user to input a cassette identifier (ID) of a tape cassette and a bin number to a cassette move window upon traveling the tape cassette from one shelf to another shelf.
The library system uses a fiber channel connected with coaxial cables or optical fiber cables that allows data to be transferred to a host computer at high speed.
For example, as shown in FIG. 1, a host computer 41 and a library system 42 are connected through the Fiber Channel (FC). The library system 42 is composed of a converter 43 and tape drives 44 and 45. In the library system 42, data that is reproduced by the tape drives 44 and 45 is supplied to the converter 43 through the Small Computer System Interface (SCSI). The converter 43 converts SCSI format data into fiber channel format data and supplies the converted fiber channel format data to the host computer 41.
Since the library system 42 uses the SCSI whose data transfer speed is much slower than that of the fiber channel, the performance of the fiber channel that connects the host computer 41 and the library system 42 cannot be fully used.
In contrast, a library system that has a plurality of tape drives using a fiber channel interface (these tape drives are referred to as FC drives) is known. Each FC drive has been assigned a World Wide Name (WWN) as a unique ID upon production thereof. Since each FC drive has been assigned a WWN that is unique in the world, a WWN that has been assigned cannot be changed after the FC drive was marketed.
However, if an FC drive becomes defective and is replaced with a substitute FC drive, the WWN of the defective FC drive is changed to the WWN of the substitute FC drive.
Since the host computer uses WWNs to manage FC drives, only by replacing the defective FC drive with a substitute FC drive, the substitute FC drive cannot be used. To use the substitute FC drive, it is necessary to change the management content of the WWNs registered in the host computer and then reboot the host computer.
However, if the host computer is mission critical, namely operates 24 hours a day, 365 days a year, it could not be easily rebooted. Thus, the replaceability of an FC drive on site would be very bad.
In addition, if the WWN of the substitute FC drive is assigned to the defective FC drive, since the WWN of the defective FC drive has been uniquely assigned in the world upon production thereof, the WWNs of the FC drives should be managed worldwide. Thus, it was difficult to replace a defective FC drive with a substitute FC drive.